Update QA label in English translations

Changed the 'qa' field in translation.json from 'Ask a question' to 'M&A Advanced AI Chat with RAG' to better reflect the feature's purpose.

Author: CWade3051

app/frontend/src/locales/en/translation.json

@@ -2,7 +2,7 @@
     "pageTitle": "Azure OpenAI + AI Search",
     "headerTitle": "Azure OpenAI + AI Search",
     "chat": "Chat",
-    "qa": "Ask a question",
+    "qa": "M&A Advanced AI Chat with RAG",
     "login": "Login",
     "logout": "Logout",
     "clearChat": "Clear chat",